Performance optimal processor throttling under thermal constraints

We derive analytically, the performance optimal throttling curve for a processor under thermal constraints for a given task sequence. We found that keeping the chip temperature constant requires an exponential speed curve. Earlier works that propose constant throttling only keep the package/case temperature constant, and are hence suboptimal. We develop high-level thermal and power models that are simple enough for analysis, yet account for important effects like the power-density variation across a chip (hotspots), leakage dependence on temperature (LDT), and differing thermal characteristics of the silicon die and the thermal solution. We use a piecewiselinear approximation for the exponential leakage dependence on temperature, and devise a method to remove the circular dependency between leakage power and temperature. To solve the multitask speed control problem, we first solve analytically, the single task problem with a constraint on the final package temperature using optimal co...

• Type: Conference
• Year: 2007
• Where: CASES
• Authors: Ravishankar Rao, Sarma B. K. Vrudhula
• Keywords: CASES 2007, Final Package Temperature, Optimal Throttling Curve, System Software, Thermal